A number of attempts have been made at imparting a hygroscopic property, a water absorbing property, a water conducting property or an antistatic property, etc., to synthetic polymers by processing the polymers so they have a hydrophilic property. One of the most widely known proposals involves a process which comprises blending a modifier, particularly, a polyalkylene oxide compound with a synthetic polymer.
However, when incorporating the modifier in the synthetic polymer, the following problems are frequently pointed out: (1) the durability of the hydrophilic effect is inferior because the modifier falls off due to heat treatment, hot water treatment, dyeing treatment, friction or use for a long time, etc., (2) inversely, the modifier is restricted in the synthetic polymer to reduce its mobility, by which it is difficult to exhibit its hydrophilic effect, and (3) the compatibility of the modifier with the synthetic polymer is not sufficient, by which it is difficult to disperse the modifier by mixing, which deteriorates workability and properties of the products.
As a result of earnest studies relating to these problems, the present inventors have found that compositions having suitable dispersibility and bleeding property are formed by the presence of a zwitterion structure and a polyalkylene oxide component in a specified state, by which there are obtained products having good and lasting hydrophilic characteristics and durability thereof.